But why is this highly popular tourist attraction -- which, by the way, requires every visitor to watch a ten minute orientation video before entering -- more vulnerable for drowning deaths? Lifeguards say that it's not because of strong currents or massive waves. The biggest danger tourists face at Hanauma Bay is the assumption that exploring the vibrant reef and marine life will be a breeze.

"[Snorkeling is] very simple to do," John Garchar, a visitor from Ohio tells KITV. "It's basically just floating in the water."

Garchar's assumption can be deadly for inexperienced swimmers. This year, four people have died while snorkeling at Hanauma Bay.

“People think it's a very benign activity, [where] you just kind of float face down and everything happens," said Jim Howe, ocean safety chief of operations. "The reality is very different. Snorkeling is quite strenuous."

According to Howe, many of the drowning victims are in their seventies or older and were actually in three feet of water or less -- enough to stand up and save themselves.

For lifeguards, it's difficult to spot a drowning victim among hundreds of people who are already swimming face down in the water. “[There's] no yelling, no screaming, no waving, no signs of distress. They just stop in the water," said Howe.

The best way to enjoy Hawaii's ocean activities is to follow the basic rules of the water below.

1. When in doubt, don't go out!

2. Never go out farther than you can swim

3. Make sure that you actually know how to swim

4. Know your physical limits and endurance

5. Pay attention to all posted beach signs -- they are there for a reason